Trace Dual-Salt Electrolyte Additive Enabling a LiF-Rich Solid Electrolyte Interphase for High-Performance Lithium...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• The solid electrolyte interphase (SEI) composition and properties are critical for lithium metal battery cyclability.
• Existing lithium metal anodes face challenges with dendrite formation and limited cycling stability.

Purpose of the Study:

• To develop a novel electrolyte additive for improving the SEI layer in lithium metal batteries.
• To enhance the electrochemical performance, cycling stability, and energy density of lithium metal anodes.

Main Methods:

• Introduction of a trace dual-salt electrolyte additive (TDEA) into the electrolyte.
• Analysis of SEI composition and morphology, focusing on lithium fluoride (LiF) distribution.
• Electrochemical testing of lithium metal anodes and Li∥NCM811 full cells with TDEA-based electrolytes.
• Evaluation of pouch cell performance under stringent cycling conditions.

Main Results:

• TDEA accelerates LiF production and promotes earlier LiF precipitation, forming a LiF-rich SEI on the lithium anode.
• TDEA suppresses lithium dendrite formation, alters deposited lithium morphology, and increases cycling time and current density.
• Li∥NCM811 full cells with TDEA showed double the lifespan compared to cells without additives.
• TDEA-enabled electrolytes achieved a high energy density of 347 Wh kg^-1 in 500-mAh pouch cells, cycling stably for over 180 cycles.

Conclusions:

• The trace dual-salt electrolyte additive (TDEA) strategy effectively improves the SEI layer for enhanced lithium metal battery performance.
• TDEA offers a promising approach for developing high-performance, stable, and high-energy-density lithium metal batteries.